There's not enough acetylene on the surface of Titan, the largest moon of Saturn. While that's probably not enough to get most of us too excited, the possible cause of the missing acetylene could be: life.

Titan is big and cold, and it's surrounded by a thick atmosphere. Liquid methane fills lakes on its surface, and carves rivers and streams.

Over the last few years, scientists have speculated that Titan could host an exotic form of life based on methane instead of water. Not only is methane abundant on Titan, but so is an exotic brew of other organic compounds -- including acetylene.

But observations by the Cassini spacecraft show that there's not as much acetylene as scientists expected. It probably "rains" from clouds on Titan, but once it reaches the surface, it vanishes. A recent study suggests the compound may be gobbled up by microscopic organisms on the surface.

What's more, a second study found that hydrogen seems to be vanishing from the surface, too. A lot of hydrogen flows from the upper atmosphere down to the surface, but it doesn't seem to stay there. The study says that organisms could use the hydrogen the same way that life on Earth uses oxygen.

No one is jumping to any conclusions just yet. Chemical reactions that don't involve life could also explain at least some of what's happening on Titan. But the studies open up the possibility that a new form of life could inhabit this intriguing world.